Acute coronary or carotid syndromes are a major cause of death in Western societies. Even in case of an initial survival of such a cardiovascular event, many patients suffer from life-threatening complications such as intravascular thrombosis leading to further myocardial infarction or stroke.
The interaction between collagen and platelets is one of the first events of the normal haemostatic response to injury. Collagen is the major extracellular matrix protein present in the subendothelium of blood vessels. Collagen binds directly to platelets via specific platelet receptors such as integrin, collagen receptor, glycoprotein IV and GPVI.
The disruption of the atherosclerotic plaque initiates a cascade of events culminating in arterial thrombosis and ischemia of the downstream tissue, precipitating diseases such as myocardial infarction or ischemic stroke. The first response to vascular injury is adhesion of circulating platelets to exposed subendothelial matrix proteins, which triggers subsequent platelet aggregation. Among the macromolecular components of the subendothelial layer, fibrillar collagen is considered the most thrombogenic constituent, as it acts as a strong activator of platelets and supports platelet adhesion both in vitro and in vivo (Baumgartner, H. R. (1977) Platelet interaction with collagen fibrils in flowing blood. I. Reaction of human platelets with alpha chymotrypsin-digested subendothelium. Thromb Haemost 37, 1-16; Clemetson, K. J., Clemetson, J. M. (2001) Platelet collagen receptors. Thromb. Haemost. 86, 189-197; Massberg, S., Gawaz, M., Grüner, S., Schulte, V., Konrad, I., Zohlnhöfer, D., Heinzmann, U., Nieswandt, B. (2003) A crucial role of glycoprotein VI for platelet recruitment to the injured arterial wall in vivo. J. Exp. Med. 197, 41-49).
Intravascular thrombosis is the result of aggregation of platelets in a vessel whereby the blood flow in the vessel may be seriously reduced or even completely inhibited. Specifically, the disruption of an atherosclerotic plaque initiates a cascade of events culminating in arterial thrombosis and ischemia of the downstream tissue, precipitating diseases such as myocardial infarction or ischemic stroke. The first response to vascular injury is adhesion of circulating platelets to exposed subendothelial matrix proteins, which triggers subsequent platelet aggregation. Among the macromolecular components of the subendothelial layer fibrillar collagen is considered the most thrombogenic constituent, as it acts as a strong activator of platelets and supports platelet adhesion both in vitro and in vivo (1-3).
The platelet membrane proteins, which have been reported to be putative collagen receptors, may be divided into those which interact indirectly with collagen through collagen-bound von Willebrand factor (vWf), including GPIbα and the integrin αIIbβ3, and those which interact directly with collagen including GPVI, the integrin α2β1 and CD36 (reviewed in (2)). Only recently, the platelet glycoprotein VI (GPVI) has been identified as the major platelet collagen receptor (4). GPVI is a 60-65 kDa type I transmembrane glycoprotein, which belongs to the immunoglobulin superfamily (5; 6). In human and mouse platelets GPVI forms a complex with the FcR γ-chain at the cell surface (7; 8). Ligand binding to GPVI triggers tyrosine phosphorylation of the ITAM motif of the Fc receptor γ chain initiating downstream signaling via Syk kinases, LAT, SLP-76, and phospholipase C (9-13). Platelets deficient in GPVI show loss of collagen-induced adhesion and aggregation in vitro (4; 14). Likewise, function blocking anti-GPVI monoclonal antibodies attenuate ex vivo platelet aggregation in response to collagen and collagen-related peptide CRP, which mimics collagen triple helix (15; 16).
It is known that the problem of complications due to the aggregation of platelets can be addressed by administering inhibitors of platelet aggregation. For the treatment of acute coronary syndromes, GP IIb/IIIa inhibitors such as ReoPro significantly improve the outcome of patients. However, a recent meta-analysis of clinical trials revealed a significant remaining risk for death or myocardial infarction despite optimal antithrombotic intervention (Boersma E, Harrington R A, Moliterno D J, White H, Theroux P, Van de Werf F, de Torbal A, Armstrong P W, Wallentin L C, Wilcox R G, Simes J, Califf R M, Topol E J, Simoons M L. Platelet glycoprotein IIb/IIIa inhibitors in acute coronary syndromes: a meta-analysis of all major randomised clinical trials. Lancet 2002; 359:189-98). Specific severe side effects of this therapeutic regimen are bleeding complications. These occurred in 2.4% of the patients with the most severe form of intracranial bleeding occurring in almost 0.1% of the treated patients. Several mechanistic shortcomings of the GP IIb/IIIa receptor blockade have been revealed which account for suboptimal effectivity and side effects. (Dickfeld T, Ruf A, Pogatsa-Murray G, Muller I, Engelmann B, Taubitz W, Fischer J, Meier O, Gawaz M. Differential anti-platelet effects of various glycoprotein IIb-IIIa antagonists. Thromb Res. 2001; 101:53-64. Gawaz M, Neumann F J, Schomig A. Evaluation of platelet membrane glycoproteins in coronary artery disease: consequences for diagnosis and therapy. Circulation. 1999; 99:E1-E11). Besides their ability to aggregate, platelets play a crucial role for the induction of atherosclerosis (Ruggeri Z M. Platelets in atherothrombosis. Nature Medicine 2002; 8: 1227-1234). The interaction of platelets with the endothelium via secretion of a wide variety of different vaso-active and pro-inflammatory substances from intracellular storage vesicles is of prominent importance (Massberg S, Brand K, Grüner S, Page S, Müller E, Müller I, Bergmeier W, Richter T, Lorenz M, Konrad I, Nieswandt B, Gawaz M. A Critical Role of Platelet Adhesion in the Initiation of Atherosclerotic Lesion Formation. J. Exp. Med. 2002, 196, Number 7: 887-896). Moreover GPIIb/IIIa antagonists have no influence on the release mechanism of platelet or even enhance pro-inflammatory responses such CD 40L or P-Selectin expression (for review see Bhatt D L and Topol E J. Scientific and therapeutic advances in antiplatelet therapy. Nature Reviews Drug Discovery 2003; 2: 15-28).
The inhibition of platelet aggregation leads to a general impairment of the platelets with regard to their ability to aggregate. Accordingly, not only the undesired thrombosis formation is influenced, but also the general ability of the platelets to terminate bleeding. Therefore, the administration of inhibitors of platelet aggregation inherently leads to severe side effects such as bleedings which may cause further life-threatening complications. These side effects are of course still more problematic in patients suffering from diabetes.
Diabetes is one of the main risk factors for atherosclerosis. Additionally diabetes constitutes an increased risk of life threatening complications and excess morbidity in patients presenting with acute vascular and especially coronary syndromes. Diabetic patients with unstable angina present with a higher incidence of plaque ulceration and intracoronary thrombosis compared to non-diabetic patients. (Biondo-Zoccai G G L; Abbate A; Liuzzo G, Biasucci L: Atherothrombosis, inflammation, and diabetes. J Am Coll Cardiol 41; 1071-1077; 2003).
It is increasingly recognized that platelets are a major trigger for the progression of atherosclerosis. The link between increased atheroprogression, and increased platelet responsiveness and diabetes is so far an unresolved problem. Diabetic patients suffer from acute vascular complications independent of the degree of atherosclerosis indicative of different presently unknown mechanisms for platelet activation in the development of diabetic acute vascular complications and atherosclerotic acute vascular complications.
Antibodies directed against GPVI have been previously reported to induce platelet activation (Schulte, V., Snell, D., Bergmeier, W., Zirngibl, H., Watson, S. P., Nieswandt, B. (2001) Evidence for two distinct epitopes within collagen for activation of murine platelets. J. Biol. Chem. 276, 364-368) and immuno-thrombocytopenia, hampering their use in the clinical setting.
WO 01/16321 and WO 01/00810 and WO 00/68377 disclose a DNA and protein sequence of the human GPVI receptor. WO 03/05020 discloses specific binding members directed against the human glycoprotein VI (GPVI) and specific inhibitors of collagen-induced platelet aggregation. Antibodies of the single chain format and in particular single chain antibodies with a particular sequence are also disclosed. EP 1224942 and EP 1228768 disclose a monoclonal anti-GPVI antibody JAQ1, which specifically binds to mouse GPVI, for the treatment of thrombotic disease. JAQ1 antibody induces irreversible internalization of the GPVI receptor on mouse platelets. This mechanism has only been observed in mice and cannot be used in a patient. EP 1224942 does not disclose the humanized form of JAQ1 and does not provide data in man or human platelets. WO 03/008454 and WO 01/00810 disclose polypeptides, proteins and fusion proteins of GPVI as a pharmaceutical composition. Moreover, antibodies and single chains against GPVI are suggested.
Therefore, the present disclosure aims to provide a medicament which is useful for avoiding life-threatening complications subsequent to an acute coronary or carotid syndrome while maintaining the potency of the blood for hemostasis.
Moreover, the present disclosure aims to provide an active agent useful for preventing or treating chronic atherosclerotic disease. Moreover, the present disclosure aims to provide an inhibitor of glycoprotein VI, notably human glycoprotein VI, which does not activate the GPVI receptor by intrinsic antibody activity and which does not induce immuno-thrombocytopenia. Moreover, the present disclosure aims to provide an inhibitor for the release mechanism of platelets and the expression of pro-inflammatory responses.
The present disclosure aims to provide a medicament for the treatment or prevention of atheroprogression.
The present disclosure aims to provide a medicament for the treatment of diabetes, notably complications associated with diabetes.
The present disclosure aims to provide an in vitro screening method for inhibitors of adhesion of platelets to intravascular lesions.
The present invention is directed to a purely inhibitory anti-GPVI antibody or function-conservative fragments or variants thereof for the treatment of acute vascular diseases. Moreover, the invention addresses the problem of providing a pharmaceutical composition for the treatment of acute vascular complications such as intra-vascular thrombosis especially in patients with atherosclerosis and/or acute endothelial lesions. Moreover, the present invention addresses the problem of providing a pharmaceutical composition for the treatment of chronic coronary artery and peripheral vessel disease. The present invention provides a pharmaceutical composition for the treatment of acute coronary, carotid artery and peripheral vessel diseases as well as chronic atherosclerosis, wherein the medicament contains a specific optionally humanized antibody hGP 5C4, or a fragment thereof, notably an Fab fragment, a function-conservative variant thereof, a fusion protein or conjugate thereof.
Citation of any document herein is not intended as an admission that such document is pertinent prior art, or considered material to the patentability of any claim of the present application. Any statement as to content or a date of any document is based on the information available to applicant at the time of filing and does not constitute an admission as to the correctness of such a statement.